U.S. patent application number 11/909483 was filed with the patent office on 2009-03-05 for security sensor device having frost protective step.
This patent application is currently assigned to Optex Co., Ltd.. Invention is credited to Hiroyuki Ikeda.
Application Number | 20090059483 11/909483 |
Document ID | / |
Family ID | 37073295 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090059483 |
Kind Code |
A1 |
Ikeda; Hiroyuki |
March 5, 2009 |
SECURITY SENSOR DEVICE HAVING FROST PROTECTIVE STEP
Abstract
In a security sensor device an element unit (21) including a
sensor elements (15, 23) for transmitting or receiving a detection
wave (IR) is supported on a sensor body (41) in such a manner as to
adjust a horizontal deflecting angle and a vertical deflecting
angle .theta.v; a cover (43) is attached to the sensor body; and
the center of pivotal movement (10) for the vertical deflection is
displaced downward or upward from the intermediate portion of the
element unit. A recessed portion (56) recessed inwardly of the
cover is formed in a part of the cover corresponding to the part,
to which the center of pivotal movement of the element unit is
displaced, through a stepped portion (44). A hood (17) for
shielding a part of the region, where the detection wave passes
for, from the airy region is provided above and near the center of
pivotal movement.
Inventors: |
Ikeda; Hiroyuki; (Shiga,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
Optex Co., Ltd.
Otsu-shi, Shiga
JP
|
Family ID: |
37073295 |
Appl. No.: |
11/909483 |
Filed: |
March 29, 2006 |
PCT Filed: |
March 29, 2006 |
PCT NO: |
PCT/JP2006/306461 |
371 Date: |
September 24, 2007 |
Current U.S.
Class: |
361/679.01 |
Current CPC
Class: |
G08B 13/183 20130101;
G08B 29/18 20130101 |
Class at
Publication: |
361/679.01 |
International
Class: |
H05K 7/00 20060101
H05K007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2005 |
JP |
2005-096899 |
Claims
1. A security sensor device which comprises: a sensor body; an
element unit including a sensor element for transmitting or
receiving a detection wave, the element unit being supported by the
sensor body for adjustment of a horizontal deflecting angle and a
vertical deflecting angle; a cover mounted on the sensor body for
covering the element unit; a center of pivotal movement for
vertical deflection in the element unit being set to an eccentric
position downwardly or upwardly displaced from a portion of the
element unit intermediate in a vertical direction thereof; a
stepped portion; a recessed portion, which is recessed inwardly of
the cover beyond a neighboring portion, being formed through the
stepped portion in a portion of the cover on one side to which the
center of pivotal movement of the element unit is displaced; and a
hood provided at a location upwardly of the center of pivotal
movement in the cover for shielding at least a portion of an area
of passage of a detection wave for the sensor element from an airy
region.
2. The security sensor device as claimed in claim 1, further
comprising a non-recessed portion of the cover defined above the
stepped portion, wherein the hood is supported by the non-recessed
portion.
3. The security sensor device as claimed in claim 1, wherein the
detection wave is an infrared beam, wherein the element unit
includes upper and lower optical elements for transmitting or
receiving the infrared beam and wherein the hood is operable to
accomplish the shielding to one of the optical elements positioned
on one side to which the center of pivotal movement is
displaced.
4. The security sensor device as claimed in claim 3, further
comprising an additional hood provided in the cover for
accomplishing the shielding to the other of the optical elements.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a security sensor device of
a type including a cover provided with a frost protective stepped
portion and a frost protective hood fitted to a portion of the
cover adjacent the frost protective stepped portion.
BACKGROUND OF THE INVENTION
[0002] This type of security sensor device is known, in which an
infrared beam transmitter and an infrared beam receiver are
arranged at respective opposite ends of a linear alert regions and,
while an infrared beam travels from the infrared beam transmitter
towards the infrared beam receiver, an entry of a human body into
the alert region can be detected once the human body intercepts the
infrared beam then traveling from the infrared beam transmitter
towards the infrared beam receiver. The infrared beam transmitter
and the infrared beam receiver in the security sensor device are of
the substantially same appearance with each other (see, for
example, the Japanese Laid-open Patent Publication No. H
10-039043).
[0003] The infrared beam transmitter or receiver such a security
sensor device is known, in which a hood or a step is provided to
prevent the sky light from impinging upon an optical lens of the
beam transmitter and receiver. Accordingly, a portion of a light
permeable surface of the cover, through which light is allowed to
enter the optical lens, is suppressed from undergoing a radiative
cooling as it is shielded from the sky, where a temperature is low,
and, therefore, during the winter, a frost is prevented from
depositing on the light permeable surface of the cover under the
influence of radiative cooling to thereby avoid cutting off the
infrared beam by the deposited frost.
SUMMARY OF THE INVENTION
[0004] However, in order to enhance such a frost protective effect,
it is necessary to employ a hood of a type protruding a substantial
distance from the cover or a cover having a large step, and the use
of the hood or cover of such size will result in increase of the
size of the security sensor device as a whole.
[0005] The present invention has been devised with the foregoing
problems inherent in the conventional art taken into consideration
and is intended to provide a security sensor device having an
excellent frost protective effect without incurring any increase in
size thereof.
[0006] In order to accomplish the foregoing object, the security
sensor device of the present invention includes an element unit
including a sensor element for transmitting or receiving a
detection wave, the element unit being supported by a sensor body
for adjustment of a horizontal deflecting angle and a vertical
(upward and downward) deflecting angle; a cover mounted on the
sensor body for covering the element unit; a center of pivotal
movement for vertical deflection in the element unit being set to
an eccentric position downwardly or upwardly displaced from a
portion of the element unit intermediate in a vertical direction
thereof; a recessed portion, which is recessed inwardly of the
cover beyond a neighboring portion, formed through a stepped
portion in a portion of the cover on one side to which the center
of pivotal movement of the element unit is displaced; and a hood
provided at a location upwardly of the center of pivotal movement
in the cover for shielding at least a portion of an area of passage
of a detection wave for the sensor element from an airy region.
[0007] According to the foregoing construction, the center of
pivotal movement of the element unit is provided eccentrically
downwardly or upwardly relative to the point of the element unit
intermediate of the vertical direction. Therefore, when the element
unit has its horizontal deflecting angle changed within a
predetermined angle range while its vertical deflecting angle is
maximized, the path of angular movement of the element unit depicts
a minimum diameter within a horizontal plane of an outer end on the
side to which the center of pivotal movement has been displaced and
the path of pivotal movement depicts a maximum diameter within a
horizontal plane of the other outer end opposite thereto, resulting
in a difference between the respective paths of pivotal movement of
the opposite ends of the vertical direction. Accordingly, that
portion of the cover on the side to which the center of pivotal
movement has been displaced and any other portion can be formed to
a shape as small as possible enough to encompass the minimum
diameter of the path of pivotal movement and the maximum diameter
of the path of pivotal movement of the element unit, respectively,
with the step of a size large enough to correspond to the
difference between the minimum and maximum diameters of the path of
pivotal movement of the element unit.
[0008] Accordingly, even though the same hood as that used
conventionally is employed, the amount of protrusion of the hood in
a direction outwardly from the recessed portion through which the
detection wave passes, is greater by a value corresponding to the
size of the stepped portion than the conventional sensor device.
Hence, the effective frost protective area, which is defined in the
recessed portion and which is shielded by the hood from the airy
region, can have a vertical width that is so large as to increase
the frost protective effect to thereby suppress any possible
reduction in amount of passage of the detection wave through the
cover. Also, a portion of the cover opposite to the side, to which
the center of pivotal movement of the element unit is displaced for
the vertical deflection, is required to have a shape greater than
the external form of the conventional cover in correspondence with
the maximum pivotal path diameter of the element unit. However,
since the angle range of vertical deflection of the element unit is
small (usually not greater than 10.degree.), it is possible to
restrict to the external form slightly larger than the conventional
cover. For this reason, there is substantially no possibility of
the overall outer form being increased in size.
[0009] In the present invention, the hood may be preferably
supported on a non-recessed portion of the cover defined above the
stepped portion. According to this construction, since the amount
of protrusion of the hood as viewed from the detection wave passing
area in the recessed portion of the cover represents the sum of the
length of protrusion of the hood plus the depth of the stepped
portion, it is possible to assuredly set the vertical width of the
effective frost protective area, defined in the detection wave
passing area of the cover, to a large value.
[0010] In the present invention, the detection wave may preferably
be an infrared beam, in which case the element unit includes upper
and lower optical elements for transmitting or receiving the
infrared beam and the hood is operable to accomplish the shielding
to one of the optical elements positioned on one side to which the
center of pivotal movement is displaced. According to this
construction, with respect to at least one of the upper and lower
optical elements, an effective frost protective area, at which
deposition of a frost is prevented, can be increased to effectively
suppress a reduction of the amount of the detection wave passing
across the cover.
[0011] In such case, an additional hood may be provided in the
cover for accomplishing the shielding to the other of the optical
elements. In order to suppress an increase in size of the external
form of the cover as a whole, it is preferred to reduce the amount
of protrusion from the detection wave passing area of the cover to
a value smaller than the hood in the cover that is positioned on
the side to which the center of pivotal movement of the element
unit is displaced. Even though the amount of protrusion is so
reduced, a possible reduction of the amount of the detection wave
passing through the cover in the other optical element resulting
from the deposit of the frost can be suppressed to a certain extent
that failure of the sensor element corresponding to the one of the
optical elements can be complemented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In any event, the present invention will become more clearly
understood from the following description of preferred embodiments
thereof, when taken in conjunction with the accompanying drawings.
However, the embodiments and the drawings are given only for the
purpose of illustration and explanation, and are not to be taken as
limiting the scope of the present invention in any way whatsoever,
which scope is to be determined by the appended claims. In the
accompanying drawings, like reference numerals are used to denote
like parts throughout the several views, and:
[0013] FIG. 1 is a circuit block diagram showing a security sensor
device according to a first preferred embodiment of the present
invention;
[0014] FIG. 2a is a right side view of the security sensor device
with a portion of a beam receiver cut out;
[0015] FIGS. 2b and 2c are right side views of the beam receiver
with a cover removed, showing an element unit held at different
angles of vertical deflection relative to a sensor body,
respectively;
[0016] FIG. 3 is a front elevational view, showing the beam
receiver with a cover removed;
[0017] FIG. 4 is a longitudinal sectional view of an essential
portion of the beam receiver;
[0018] FIG. 5a is a top plan view of a beam receiver of the
security sensor device;
[0019] FIG. 5b is a front elevational view of the beam
receiver;
[0020] FIG. 5c is a bottom plan view of the beam receiver;
[0021] FIG. 5d is a right side view of the beam receiver;
[0022] FIG. 5e is a longitudinal sectional view of an essential
portion of the beam receiver;
[0023] FIGS. 6a to 6d are a top plan view, a front elevational
view, a bottom view and a right side view, respectively, showing
the beam receiver of a modified form of the security sensor device
according to the first preferred embodiment of the present
invention;
[0024] FIG. 7a is a right side view showing the beam receiver of
the security sensor device according to a second preferred
embodiment of the present invention, with a portion thereof cut
out; and
[0025] FIGS. 7b and 7c are right side views of the element unit
held at different angles of vertical deflection relative to the
sensor body, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Hereinafter, preferred embodiments of the present invention
will be described with particular reference to the accompanying
drawings.
[0027] FIG. 1 is a circuit block diagram showing a security sensor
device according to a first preferred embodiment of the present
invention.
[0028] The security sensor device shown therein is an infrared
detecting device of an active type including a beam transmitter 1
and a beam receiver 2 mounted respectively on wall surfaces or
poles at opposite ends of a linear alert region in optically
aligned relation with each other, and is capable of transmitting
and receiving an infrared beam IR as a detection wave for detecting
a human body. When the beam receiver 2 detects the infrared beam
transmitted from the beam transmitter 1, but intercepted by a human
body, the presence of the human body can be detected. The beam
transmitter 1 and the beam receiver 2 are of a structure unitized
together as will be described later.
[0029] The beam transmitter 1 includes a transmitting side element
unit 11, a transmitter drive circuit 12, a transmission control
circuit 13, and a transmitting side cover open/close detection
switch 14. Each of the element unit 11, the transmitter drive
circuit 12 and the transmission control circuit 13 is provided in a
plural number, for example, in a pair, but only one is shown in
FIG. 1. The element unit 11 includes a beam emitting element 15
such as, for example, an infrared light emitting diode and a
transmitter optical element 16 such as, for example, a beam
transmitting lens or a reflective mirror for forming an infrared
beam IR such as, for example, a near infrared beam. The element
unit 11 operates as a beam transmitter. The transmitter drive
circuit 12 is operable to drive the beam emitting element 15 at a
predetermined frequency to cause the beam emitting element 15 to
emit the infrared beam IR made up of pulse modulated waves. The
transmitting side cover open/close detection switch 14 is a contact
type or proximity type switch for detecting selective opening or
closure of the cover relative to the sensor body as will be
described later. The transmission control circuit 13 is operable,
when the cover open/close detection switch 14 detects the opening
of the cover, to control the transmitter drive circuit 12 so that
an electric drive power reduced by an amount corresponding to the
quantity of the infrared beam from the beam emitting element 15,
which is transmitted having been attenuated by the cover, can be
supplied to the beam emitting element 15.
[0030] On the other hand, in the beam receiver 2, the receiving
side element unit 21 includes a receiver optical element 22 such
as, for example, a beam receiving lens or a beam collecting mirror
and a beam receiving element 23 such as, for example, a
phototransistor. The receiving side element unit 21 operates as a
beam receiver. This receiving side element unit 21 is operable to
receive the infrared beam IR from the beam transmitter section 1
and to output an electric signal proportional to the amount of the
infrared beam received thereby. This electrical signal is, after
having been amplified by an amplifying circuit 24, supplied to a
detection circuit 25, by which an external disturbance light is
removed and the electrical signal is converted into a signal
proportional to the level of the received beam signal and in the
form of only a pulse modulated wave. This signal outputted from the
detection circuit 25 is then supplied to a signal judging circuit
26, where a decision is made to determine if this signal level is
lower than a predetermined detection level. In the event that the
level of the received beam signal is lower than a predetermined
detection level as a result of the infrared beam IR from the beam
transmitter 1 having been intercepted by an unauthorized intruder,
the signal judging circuit 26 outputs a detection signal to an
alarm circuit 27 to trigger the latter to provide, for example, a
security center (not shown) with a warning signal indicative of the
presence of the unauthorized intruder.
[0031] Also, the signal level proportional to the amount of the
infrared beam received by the element unit 21 is displayed by a
level meter 29 such as, for example, a voltmeter electrically
connected with the detection circuit 25. In addition, the amplifier
24 has its gain controlled by an AGC circuit 30 in accordance with
the signal level of the received beam signal fed from the element
unit 21 so that the output from the amplifier 24 can be lower than
a certain signal level at all times. Although each of the element
unit 21, the amplifier 24, the detection circuit 25, the signal
judging circuit 26 and the level meter 29 is also provided in a
plural number, for example, in a pair, only one thereof is shown in
FIG. 1. The beam receiver 2 also includes a receiving side cover
open/close detection switch 31 and a receiving level control
circuit 32. The receiving side cover open/close detection switch 31
is a contact type or proximity type switch for detecting selective
opening or closure of the cover, as will be described later,
relative to the sensor body. The receiving level control circuit
32, when the cover open/close detection switch 31 detects the
opening of the cover, lowers the gain of the amplifier circuit 24
through the AGC circuit 30 so that the amplifier circuit 24 can be
controlled to amplify the signal level of the received beam signal
from the element unit 21 by reducing such signal level by a
quantity corresponding to the quantity attenuated by the cover.
[0032] Each of the beam transmitter 1 and the beam receiver 2, both
referred to above, is unitized to represent the same outer shape.
Accordingly, only the beam receiver 2 shown in FIGS. 2a to 2c will
be described in detail as a representative example. This beam
receiver 2 includes a sensor body 41 and a cover 43. The sensor
body 41 is made of a resinous material and mounted on a support
surface S such as, for example, a wall surface or a pole as shown
in FIG. 2a, and the cover 43 is also made of a resinous material
and removably capped onto a base 42 of the sensor body 41.
[0033] The receiving side element unit 21 includes upper and lower
receiver optical elements 22 each comprised of a beam receiving
lens and retained by a unit casing 45, a first circuit substrate 46
mounted inside the unit casing 45, and upper and lower beam
receiving elements 23 surface mounted on the first circuit
substrate 46 at respective locations rearwardly of the associated
receiver optical elements 22. A second circuit substrate 47 mounted
on the base 42 has the sensor circuits 21, 24 to 27 and 29 to 32 of
respective structures shown in FIG. 1 surface mounted thereon.
[0034] A support member 7 secured to a front lower portion of the
base 42 has, as shown in a front elevational view in FIG. 3, a
U-shaped holder 8 supported thereby in a cantilever fashion for
angular movement about a vertically extending stationary pivot pin
9. The element unit 21 is mounted on this holder 8 for angular
movement about a pair of horizontally extending transverse
stationary pivot pins 10 as shown in FIG. 2a. The vertically
extending pivot pin 9 may be, for example, a screw member (FIG. 4)
and each of the transverse pivot pins 10 is a cylindrical pin.
Accordingly, the element unit 21 has its horizontally deflecting
angle adjusted when pivoted about the vertically extending pin 9
together with the holder 8 relative to the base 42, and also has a
vertically deflecting angle adjusted when pivoted about the
transverse pins 10 relative to the holder 8. Accordingly, with the
element unit 21 so pivoted, an optical alignment with the element
unit 21 can be accomplished. This optical alignment is performed by
the aid of a sighting instrument 36 as will be described later.
[0035] In the element unit 21 referred to above, the vertically
extending pivot pin 9, which defines the center of pivotal movement
about which the unit casing 45 shown in FIG. 3 undergoes a
horizontal deflection, is disposed at a portion of the holder 8
intermediate of a leftward and rightward direction (a horizontal
direction). However, the transverse pins 10 best shown in FIG. 2a
for defining the center of pivotal movement about which the unit
casing 45 undergoes a vertical deflection, are disposed at a
location displaced downwardly relative to a portion of the unit
casing 45 intermediate of an upward and downward direction (a
vertical direction). The conventional transverse pivot pins 10 have
been disposed at a portion of the unit casing 45 intermediate of an
upward and downward direction (a vertical direction).
[0036] The holder 8 referred to previously is formed integrally
with a dial 35 for turning the holder 8 about the vertically
extending pivot pin 9 in order to adjust the horizontal deflecting
angle of the element unit 21. Also, as shown in FIG. 4, a vertical
front wall 8a is integrally formed with the holder 8, and a
vertical projection 33 is formed with a rear end portion of the
unit casing 45 so as to protrude downwardly. An adjustment screw 19
is rotatably passed through the front wall 8a and is threadingly
engaged in the projection 33. A coiled spring body 34 for urging
the projection 33 and, hence, the unit casing 45 in a direction
rearwardly (in a rightward direction as view in FIG. 4) is
interposed between the projection 33 and the front wall 8a.
Accordingly, when the dial 35 is turned, the horizontal deflecting
angle of the element unit 21 can be adjusted together with the
holder 8 and, when the adjustment screw 19 is turned, the vertical
deflecting angle of the element unit 21 can be adjusted.
[0037] The sighting instrument 36 of any known construction for
aiding the optical alignment is provided at a vertically
intermediate portion of the unit casing 45 of the element unit 21,
shown in FIG. 3. This sighting instrument 36 has a sighting
instrument casing 37, left and right viewing windows 38 defined in
the sighting instrument casing 37, left and right sighting holes 39
defined in left and right portions of a front forward surface, and
left and right reflecting mirrors (not shown) disposed inside the
sighting instrument casing 37. Looking through one of the viewing
windows 38 of this sighting instrument 36 while the cover 43 is
opened, an attendant worker manually turns the dial 35 or the
adjustment screw 19 to adjust the horizontal deflecting angle or
the vertical deflecting angle. When an image of the element unit 11
of the beam transmitter 1, shown in FIG. 1, which is projected onto
one of the reflecting mirrors may overlap the sighting hole 39
shown in FIG. 3, a rough optical alignment can be accomplished.
Following this rough optical alignment, a fine adjustment of the
optical axis is carried out by adjusting the dial 35 and the
adjustment screw 19, both shown in FIG. 3, to such an extent that a
display of the level meter 29 (FIG. 1), then viewed by the
attendant worker, attains a maximum value. Until the display of the
level meter 29 shown in FIG. 1 attains a value higher than a
predetermined level, that is, the optical axis of the beam receiver
2 accurately align with the beam transmitter 1, the optical
adjustment of the beam transmitter 1 and the beam receiver 2 is
repeated a plurality of times if so required. It is to be noted
that the beam transmitter 1 is of a structure substantially
identical with that of the beam receiver 2.
[0038] On the other hand, in the cover 43 shown in FIG. 2a, a
stepped portion 44 is formed at a portion thereof confronting the
vertically intermediate portion of the element unit 21, and a
non-recessed portion 55 and a recessed portion 56 are formed above
and below the stepped portion 44, respectively. In other words, at
a portion corresponding to a downward side to which the transverse
pivot pins 10, defining the center of pivotal movement of the
element unit 21 for the vertical deflection, are offset relative to
the vertically intermediate portion of the element unit 21, the
recessed portion 56, depressed from the other non-recessed portion
55 in a direction inwardly of the cover 43, is formed through the
stepped portion 44. Also, the cover 43 is provided with a hood 17,
which is engaged in, and bonded with a bonding material to an outer
peripheral surface of the non-recessed portion 55 at a location
adjacent the stepped portion 44 in the non-recessed portion 55 on
one side above the stepped portion 44. In order to prevent the
infrared beam IR from being blocked as a result of frosting of a
beam transmissive surface (an area through which the infrared beam
IR, which is a detection wave, passes) of the cover 43, which takes
place during the winter by the effect of the radiative cooling, in
which heat is radiated from the surface of the cover 43 towards the
airy region where the temperature is low, the stepped portion 44
and the hood 17 cooperate with each other to suppress the radiative
cooling by shielding a portion of the light transmissive surface of
the cover 43 from the airy region.
[0039] Although the element unit 21 referred to above is shown to
include upper and lower optical elements 22, 22 and upper and lower
beam receiver elements 23, 23, there would be no problem in terms
of the function to detect a human body, if the amount of the
infrared beam IR passing through the cover is secured to a required
value with respect to at least one of the optical elements 22, 22
and corresponding one of the beam receiving elements 23, 23. In
other words, it is sufficient to prevent the blocking of the
infrared beam IR, which will result from deposition of a frost on a
portion of the beam transmissive surface of the cover 43, which
corresponds to at least one of the two optical elements 22, 22. In
view of this, in the illustrated embodiment, a frost protective
means made up of the stepped portion 44 and the hood 17 is provided
only to the lower optical element 22, and the details of this frost
protective means will be described later.
[0040] The variable range of the horizontal deflecting angle of the
beam receiver 2 about the center of pivotal movement defined by the
vertically extending pivot pin 9 is set to 180.degree. and the
variable range of the vertical deflecting angle .theta.v of the
beam receiver 2 about the center of pivotal movement defined by the
transverse pivot pins 10 shown in FIGS. 2B and 2C is set to
5.degree. or smaller. FIG. 2b illustrates a condition, in which the
element unit 21 is pivoted in a downwardly oriented direction to a
position at which the vertical deflecting angle .theta.v is
maximal, but FIG. 2c illustrates a different condition, in which
the element unit 21 is pivoted in an upwardly oriented direction to
a position at which the vertical deflecting angle .theta.v is
maximal. Even where the horizontal deflecting angle is changed to
180.degree. during the condition shown in either FIG. 2b or FIG.
2c, the path of angular movement of an upper end contour of the
unit casing 45 about the vertically extending pin 9 and the path of
angular movement of a lower end contour of the unit casing 45 about
the vertically extending pin 9 depict respective diameters that are
different from each other because the transverse pins 10, defining
the center of pivotal movement for the vertical deflection angle
.theta.v, are displaced downwards. In other words, in the event
that the horizontal deflecting angle is changed to 180.degree.
while the element unit 21 is held in the condition referred to
above, the diameter depicted by the path of pivotal movement of the
upper end contour of the unit casing 45 represents the maximum
diameter D1 of the path of pivotal movement of the element unit 21
and, on the other hand, the diameter depicted by the path of
pivotal movement of the lower end contour of the unit casing 45
represents the minimum diameter D2 of the path of pivotal movement
of the element unit 21.
[0041] The maximum pivotal path diameter D1 depicted by the path of
pivotal movement of the upper end contour of the unit casing 45 is
greater than that in the conventional case, in which the transverse
pivot pins 10, defining the center of pivotal movement for the
vertical deflecting angle, are set to a portion intermediate of the
vertical direction of the element unit 21. However, since the
variable range of the vertical deflecting angle .theta.v is equal
to or smaller than 5.degree., it merely increases to a value
slightly greater than the diameter of the conventional path of
pivotal movement. On the other hand, the minimum pivotal path
diameter D2 depicted by the path of pivotal movement of the lower
end contour of the unit casing 45 becomes smaller than the
diameter, depicted by the conventional path of pivotal movement, by
a quantity corresponding to the distance that the transverse pivot
pins 10, defining the center of pivotal movement for the vertical
deflecting angle .theta.v, have been offset downwardly from the
portion intermediate of the vertical direction of the unit casing
45.
[0042] FIGS. 5a to 5e illustrate a top plan view, a front
elevational view, a bottom plan view, a right side view and a
fragmentary longitudinal sectional view of the beam receiver 2. In
those figures, the non-recessed portion 55 located above that
portion of the cover 43, where the hood 17 is fitted, is so shaped
as to accommodate the maximum pivotal path diameter D1 depicted by
the upper end contour of the unit casing 45. As hereinbefore
described, since the maximum pivotal path diameter D1 merely
increases to a value slightly greater than the diameter depicted by
the path of pivotal movement in the conventional sensor device, the
non-recessed portion 55 can be set to have the contour of a size
that is substantially equal to that of the cover used in the
conventional sensor device. Accordingly, the hood 17 that is
secured to the outer surface of the non-recessed portion 55 of the
cover 43 can be of the substantially same size as the existing
hood. Thus, the security sensor device of the present invention
will not result in an increase of the overall size thereof as
compared with the conventional sensor device. The hood 17 has a
fitting area 17b and a visor portion 17a protruding outwardly from
the cover 43 and, as best shown in FIG. 5e, the fitting area 17b is
engaged in a mounting area 55a, which is defined in the outer
surface of the non-recessed portion 55 in the cover 43 so as to be
depressed somewhat inwardly, and is then fixed in position by the
use of, for example, a bonding agent.
[0043] On the other hand, the recessed portion 56 below that
portion of the cover 43, where the hood 17 is secured, has an
external form reduced in size by a quantity corresponding to the
difference between the minimum pivotal path diameter D2, depicted
by the lower end contour of the unit casing 45 shown in FIG. 2b,
and the diameter of pivotal movement in the conventional sensor
device. For this reason, the stepped portion 44 in the cover 43 as
best shown in FIG. 2a is of a size matching with the difference in
size between the non-recessed portion 55 and the recessed portion
56. As a result thereof, the amount of protrusion P1 of the visor
portion 17a in a direction outwardly from the beam transmissive
surface of the cover 43 is increased a value corresponding to the
size of the stepped portion 44 if the hood 17 of the substantially
same shape as that in the conventional sensor device is employed.
Hence, the effective frost protective area, which is defined by a
shadow of the visor portion 17a in the beam transmissive surface of
the cover 43 against the airy region, can have a vertical width A
that is so large as to increase the frost protective effect.
Accordingly, not only can the security sensor device of the present
invention be so structured as to have an overall external form that
is not increased as hereinabove described, but deposit of the frost
on a portion of the beam transmissive surface of the cover 43 can
be avoided to thereby suppress an undesirable reduction of the
amount of the infrared beam IR passing across the cover towards the
lower optical element 22, which is one of the upper and lower
optical elements 22, 22.
[0044] FIG. 6 illustrates a modified form of the first embodiment
of the present invention and component parts shown therein, but
similar to those shown in FIG. 5 are designated by like reference
numerals. In the example shown therein, in addition to the
provision of the hood 17 which is in the first embodiment used to
shield an upper region of the beam transmissive surface of the
cover 43 for the passage of the infrared beam IR for the lower
optical element 22 from the airy region, an additional hood 17A is
employed for shielding an upper region of the beam transmissive
surface of the cover 43 for the passage of the infrared beam IR for
the upper optical element 22 from the airy region. For this
additional hood 17A, a hood of the same size as that of the lower
hood 17 is employed.
[0045] According to the above construction, since the amount of
protrusion P2 of the additional hood 17A outwardly from the cover
43 remains the same as that in the conventional sensor device, the
vertical width A2 of the effective frost protective area, which is
defined in the beam transmissive surface of the cover 43 for the
passage of the infrared beam IR for the upper optical element 22,
similarly remains the same as that in the conventional sensor
device. However, the use of the additional hood 17A is effective to
suppress any possible reduction in amount of the infrared beam IR
across the cover relative to the upper beam receiving element 23
and, therefore, a failure to detect can be further
complemented.
[0046] FIG. 7 illustrates a second preferred embodiment of the
present invention and FIGS. 7a to 7c correspond respectively to
FIGS. 2a to 2c and, accordingly, component parts shown therein, but
similar to those shown in FIGS. 2a to 2c are designated by like
reference numerals. While in the first embodiment the transverse
pivot pins 10 that defines the center of pivotal movement for the
vertical deflecting angle .theta.v have been eccentrically
positioned or displaced downwardly relative to the intermediate
portion of the element unit 21, the transverse pivot pins 10 that
defines the center of pivotal movement for the vertical deflecting
angle .theta.v in this second embodiment are eccentrically
positioned or displaced the same distance as in the first
embodiment in a direction upwardly relative to the intermediate
portion of the element unit 21. Thus, a portion of the beam
transmissive surface of a cover 43A corresponding to the upper
optical element 22 can be shielded by the hood 17 from the airy
region. Accordingly, the cover 43A is of such a shape as to have
the recessed portion 56 provided in a portion thereof intermediate
of the vertical direction in alignment with the upper optical
element 22 and also as to have the non-recessed portion 55 provided
on respective sides upwardly and downwardly of the recessed portion
56.
[0047] The security sensor device according to this second
embodiment differs from that according to the first embodiment only
in respect of the manner of support of the element unit 21 and the
shape of the cover 43A and, therefore, effects similar to those
afforded by the first embodiment can be obtained. In other words,
the first embodiment merely differs from the second embodiment in
that while in the first embodiment deposition of the frost on that
portion of the cover 43 corresponding to the lower optical element
22 is prevented, in the second embodiment deposition of the frost
on that portion of the cover 43A corresponding to the upper optical
element 22 is prevented. Hence, the non-recessed portion 55 can
have the external form, which is of the substantially same size as
that of the cover used in the conventional sensor device and, at
the same time, a hood of the same size as the existing hood can be
employed. Accordingly, without incurring an increase of the overall
size, the frost protective effect similar to that afforded by the
first embodiment can be obtained by the utilization of the stepped
portion 44 of the same size as that in the first embodiment.
[0048] The present invention can be equally applied to the beam
transmitter 1 shown in FIG. 1, other than to the beam receiver 2 of
the security sensor device, which has been illustrated and
described in connection with the foregoing embodiments, and also to
a passive type infrared detector for detecting far infrared beams
and a security sensor device utilizing a conjugated detecting
technology, in which the active type and the passive type are
combined.
[0049] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings which are used only for the purpose of
illustration, those skilled in the art will readily conceive
numerous changes and modifications within the framework of
obviousness upon the reading of the specification herein presented
of the present invention. Accordingly, such changes and
modifications are, unless they depart from the scope of the present
invention as delivered from the claims annexed hereto, to be
construed as included therein.
* * * * *